A power inverter comprises mainly an inverter main circuit, a smoothing capacitor connected in parallel with a DC power supply terminal of the inverter main circuit, and a control circuit for controlling the inverter main circuit. The inverter main circuit has plural power semiconductors, and a power module is formed by predetermined number of power semiconductors as a unit. Consequently, the inverter main circuit is configured as one or more power modules each having plural power semiconductors.
As an example of configuring such a power inverter as a unit, a unit is known in which plural power modules are arranged such that their input/output terminals are aligned in the vertical direction and a smoothing capacitor is disposed near the upper central section above the input terminal.
Such a power inverter is disclosed in, for example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2003-199363).
In a field of an electric motorcar which is driven by only an electric motor without using an internal combustion engine and a hybrid powered automobile using both an internal combustion engine and an electric motor, it is desired to increase the proportion of the interior in the whole capacity of the vehicle as much as possible to improve comfortability.
Consequently, it is desired to miniaturize a control unit such that the control unit can be mounted in a space as small as possible. A power inverter electrically connected to a rotating electric machine for a vehicle is also desired to be miniaturized.
However, power of the rotating electric machine mounted on a vehicle is increasing and a heat generation amount of the power inverter is larger than that at the early stage of development. With increase in the power, the voltage used is also becoming higher. When the inductance of a main circuit is large, in many cases, surge voltage generated at the time of switching power semiconductors becomes an issue. As a solution, the withstand voltage of components may be increased. In this case, however, the whole apparatus becomes large.